Don't use the MS Backup program--use the software that came with your
burner or get a backup program that works with burners.  CD Burners did
not exist when W98 was written and W98 does not support disk spanning.

    To use a CD-R or CD-RW disc like a diskette, you need to install
"packet-writing" software that runs in the background and enables your
backup software to access the disc.  Your CD burner probably came with
software of two types: "mastering" and "packet writing."  The mastering
software, such as Ahead Nero or Roxio Easy CD Creator, is used for things
like copying entire CD discs or making custom data CDs, but with it you
can copy only from within the mastering program.  The mastering software,
however, should be accompanied by that company's corresponding packet-
writing program (InCD with Nero; DirectCD with Roxio; others like DLA are
also available).  If you install one of these, and use it to format the
disc for the UDF file system, you can then copy files to it as if it were
a floppy diskette.  Bear in mind that UDF-formatted discs will *not* be
readable in real-mode DOS (or on Windows systems without a UDF driver
installed), so if you want backups that you can use if you can't start
Windows, they should be created with mastering software in ISO9660 format.